RE: Dissimilar welding of P1 and P8 materials

In ASME VIII div.1, if the thickness of carbon steel plate is greater than 32 mm, a preheat temperature of 200F is recommened. I was wonderting whether or not to apply a preheat of 200F for the dissimalar welding of P1 material to P8 material.

RE: Dissimilar welding of P1 and P8 materials

RE: Dissimilar welding of P1 and P8 materials

Quote:

In ASME VIII div.1, if the thickness of carbon steel plate is greater than 32 mm, a preheat temperature of 200F is recommened

You have found your preheat requirement answer above for pressure retaining carbon steel material used with similar material or in a dissimilar metal weld (DMW) joint application (See Table UCS-56 in Section VIII, Div 1). The key is to set a maximum interpass temperature of 400 deg F for use in a DMW to avoid exposing the P-No 8 to high heat input.

For non-pressure retaining CS material that is welded to non-pressure retaining austenitic stainless steel, this advice would still hold for the CS and thickness. I like to use ASME Section VIII, Div 1 preheat requirements even for non-pressure retaining applications to remain consistent.

RE: Dissimilar welding of P1 and P8 materials

kissjxp;If the non-pressure part is P-No 1 material and exceeds 38mm in thickness, PWHT would be required. Now, if you are going to be welding this to a P-No 8 base material in a DMW joint, you should butter the P-No 1 weld joint with 309, PWHT the P-No 1 base material after buttering, and complete the weld joint using 308 stainless steel with no PWHT.

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